4ilm | pdb_00004ilm
CRISPR RNA Processing endoribonuclease
Structural highlights
FunctionCAS6B_SACS2 CRISPR (clustered regularly interspaced short palindromic repeat) is an adaptive immune system that provides protection against mobile genetic elements (viruses, transposable elements and conjugative plasmids). CRISPR clusters contain sequences complementary to antecedent mobile elements and target invading nucleic acids. CRISPR clusters are transcribed and processed into CRISPR RNA (crRNA). Functions as a ssRNA-specific endoribonuclease, generating an 8 base-long tag known as the 5' handle.[1] Publication Abstract from PubMedClustered regularly interspaced short palindromic repeats (CRISPRs) confer adaptive immunity to prokaryotes through a small RNA-mediated mechanism. Specific endoribonucleases are required by all CRISPR-bearing organisms to process CRISPR RNAs into small RNA that serve as guides for defensive effector complexes. The molecular mechanism of how the endoribonucleases process the class of CRISPR RNA containing no predicted secondary structural features remains largely elusive. Here, we report cocrystal structures of a processing endoribonuclease bound with a noncleavable RNA substrate and its product-like fragment derived from a nonpalindramic repeat. The enzyme stabilizes a short RNA stem-loop structure near the cleavage site and cleaves the phosphodiester bond using an active site comprised of arginine and lysine residues. The distinct RNA binding and cleavage mechanisms underline the diversity in CRISPR RNA processing. Recognition and Cleavage of a Nonstructured CRISPR RNA by Its Processing Endoribonuclease Cas6.,Shao Y, Li H Structure. 2013 Feb 27. pii: S0969-2126(13)00017-8. doi:, 10.1016/j.str.2013.01.010. PMID:23454186[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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